The invention relates to a radial shaft seal for sealing a shaft passing through a housing wall opening, comprising at least one membrane-like, annular sealing element with a sealing lip that can be positioned against the shaft in sealing fashion, a metallic, annular supporting element on which the sealing element is mounted, an edge area provided on the supporting element, which runs around the outer circumference and is not covered by the sealing element, and a centring surface provided on the outer circumference of the edge area.
A radial shaft seal with the features mentioned in the opening paragraph is known from DE 198 41 123 B4. In this known radial shaft seal, which has already proven highly successful in practice to date, both the centring surface of the circumferential edge area of the supporting element and the outer circumferential area of the sealing element are positioned against the inner wall of the housing wall opening through which the shaft passes.
The material of the sealing element preferably consists of a highly wear-resistant, elastomeric material. This material is extremely resistant to a large number of substances. The pump housings used for coolant pumps in automotive engineering are often made of thermosetting plastics. In this context, elevated operating temperatures can lead to the evolution of ammonia gas, formaldehyde gas and the like, which react with elastomeric materials and can lead to hardening of the material.